This project will continue to investigate the cellular mechanisms which control thymus-dependent (T cell) immunity in contact hypersensitivity to 2,4-dinitrofluorobenzene (DNFB). Two aspects will be emphasized. First, we will study the properties of DNFB-immune T cells. Specifically we will investigate: (1) the genetic requirements which are necessary to activate the immune cells and (2) the antigen-specific receptor(s) using an autoantiserum against the immune T cells. Second, we will investigate the biological properties of a soluble suppressor factor which specifically suppresses DNFB-immune T cells. Both in vivo (local passive transfer of DNFB immunity) and in vitro (MIF production by DNFB-immune T cells) methods will be used to analyze the various aspects of immunity and tolerance.